Tektronix Phaser 340 Service Manual page 98

5
Theory of Operation
5-6 Phaser 340 Color Printer
Prior to each print, a cam, driven by the process motor, raises the wick against
the slowly rotating drum. A compliant blade, also raised by the same cam,
assures that the oil film is smooth and even across the drum's surface. As the
drum completes one rotation, the rotating cam lowers the wick and then a
moment later, lowers the blade.
A counter gear slowly and incrementally advances a sensor interrupt flag across
the width of the maintenance tray each time the cartridge is used. When it
interrupts its sensor, it indicates the maintenance cartridge must be replaced.
(Initial shipments of maintenance trays advance a fabric roll with notches cut in
the beginning and end of the roll to signal the print engine main board of the
presence of a new or consumed tray.) The sensors are mounted on the
maintenance tray guides on the inside of the printer frame.